Drop bulb pressure-measuring device

ABSTRACT

A blood set for a dialysis system is provided with a drip bulb having flexible side walls and a transducer responsive to the relative position thereof whereby pressure within the drip bulb is ascertained.

United States Patent [1 1 Willock Oct. 15, 1974 DROP BULB PRESSURE-MEASURING [56] References Cited DEVICE UNITED STATES PATENTS [76] lnventor: Charles B. Willock, 16222 8.15. 3,756,234 9/1973 Klo 128/214 F Oatfield Rd., Milwaukie, Oreg. 97222 Primary Examiner-Donald O. Woodie] Attorney, Agent, or FirmK1arquist, Sparkman, [221 Flled- May 1973 Campbell, Leigh, Hall & Whinston [21] Appl. No; 365,474

[57] ABSTRACT A blood set for a dialysis system is provided with a g fi J E drip bulb having flexible side walls and a transducer end oi'giiijIIIIIIIIIIIII.IIIII'ii/Es 389 406- re ere rererrve rreerrrerr rrrereer whereby 128/214 C, 214 E, 214 F, DIG. 13; 210/91 pressure within the drip bulb is ascertained.

12 Claims, 3 Drawing Figures 1 v DROP BULB PRESSURE-MEASURING DEVICE BACKGROUND OF THE INVENTION A conventional dialysis system includes a drip bulb of round cross section into which a needle is inserted for connection via tubing to a conventional diaphragm SUMMARY OF THE INVENTION A drip bulb according to the present invention comprises a unitary pressure-measuring device for avoiding contamination of the transported liquid and contamination of external pressure-measuring equipment. The drip bulb is provided with a flexible wall to which a movement sensitive transducer is coupled for ascertaining the pressure within the closed drip bulb.

In accordance with apreferred embodiment of the present invention, a drip bulb having an elongate cross section and a pair of adjacent flexible walls is disposed in a frame wherein the spacing between the walls due to gaseous pressure can be measured. An electromagnetic transducer includes a movable core coupled to a support of one of said flexible walls, and a differential electrical output is produced corresponding to pressure within the bulb. 7 Y

FIG. 3 is a schematic representation of the pressuremeasuring apparatus according to the present invention including electrical circuitry associated therewith.

DETAILED DESCRIPTION Referring to the drawings, and particularly to FIGS. 1 and 2,'pressure-measuring apparatus according to the present invention comprises a U-shaped frame generally indicated at 10 including a first leg 12 and a second substantially parallel leg-.14, both of which are formed of plastic material. The rearward portion of leg 14 is extended rearwardly by a movable member 16 interfitting with leg'12 and having a notch 18 aligned with a notch 20 on leg 12 and for engaging a vertical support rod 22. The notched members are joined together in clamping relation to the support rod by means of screw threaded rod 24 engaging threads in member 12 and having a shoulder bearing against member 16. Rod 24 is provided with anadjusting knob 26 for rotating the same.

. Legs 12 and 14 are secured together with a bolt 28. Leg 12 forms the base for a somewhat flexible metal support strap 30 extending along the inside of leg 12 and secured to leg 12 by'means of a bolt 32. The support strap 30 extends beyond the open end of the U- shaped frame where it isprovided with a vertically upward opening notch 34 for receiving an attachment button 36 of drip bulb 38. Also, a second somewhat flexible metal support strap 40 is secured to leg 14 by means of bolt 42'and extends along the inside of leg 14 and beyond the open end of the U-shaped frame where Accordingly, an object of the present invention is to provide an improved pressure-measuring device for a blood set.

Another object of the present invention is to provide an improved means for ascertaining thegaseous pressure within a drip bulb. v I

It is a further object of the present invention to provide an improved, unitary, pressure-measuring drip bulb device wherein connection of remote pressure gauges to such drip bulb is avoided.

It is another object of the present invention to prothereof, may best be understood by reference to the.

following description taken in connection with the accompanying drawings wherein like reference charac' ters referto like elements. I

- ..DRAWINGS 1 FIG. 1 is a plan view, partiallybroken away, of pressure-measuring apparatus according to the present invention;

FIG. 2 is a cross-sectional view taken at 2-2 in FIG. 1; and

the support strap 40 is provided with an upward opening notch 42 for receiving a'secon'd attachment button 44 of the aforementioned drip bulb 38. Leg 12 has.

upper and lower flanges 46-which meet with upper and lower flanges 48 of leg 14 to enclose the central portion of the U-shaped frame up to a forward opening 50 where the flanges are foreshortenedso that drip bulb 38 can be partially of the U.

A'housing 52 extends at right angles to leg 14' nearthe open end of the U-shaped frame and is provided with an inside cylindrical chamber or bore 54 opening adjacent support strap 40 inside the frame. Chamber or bore 54 receives a cylindrical transducer 56 comprising a metal enclosed coil bobbin having a movable core 58 slidably received therewithin, the latter being formed of magnetically permeable material. The core 58 isthreaded on one end to receive a threaded hard rubber connecting rod 60 which is attached to support strap 40, the rod 60 extending through a small aperture in strap 40 where the two are substantially joined. Flexure' --of strap 40 moves connecting rod '60, which, in turn,

changes the axial, position of core 58 within bobbin 56.

The transducer comprising bobbin 56 and core 58 is accommodated within the opening metal strap 40. Thus, the bobbin 56 is moved by such adjustment relative to the core 58. Leaf spring 68 is secured to leg 14 by means of bolt 42, and leg 14 is relieved at 74 so that the leaf spring can be effective in moving bobbin 56 back and forth. A second adjusting screw 70, provided with a head- 72 for rotating the same, is threadably received through the opposite wall of leg 12, in substantially axial alignment with adjusting screw 64 and the transducer. Screw 70 bears against strap 30 for positioning strap 30. a

Drip bulb 38 is a container suitably elongated in the vertical direction and supported vertically so that a liquid 76, e.g., blood, intravenous solution, or the like, is held in the lower part thereof. Ingress of liquid is provided via tube 78 secured toplastic cap '80 while egress of liquid is provided by tube 82 joined to lower funnelshaped outlet 84 of the drip bulb, wherein tubes 78 and 82 may form part of a blood set utilized in dialyzer operation of the like. The liquid is conventionally introduced via tube 78 as dropletsfalling to liquid level 76 through a gaseous region or air space 86 thereabove.

The drip bulb according to the present invention is desirably elongateor flattened in cross section as illustrated in FIG. 3 so as to be provided with flexible, facing side walls 88 and 90 of larger dimension, and shorter curved end walls 92 and 94. The drip bulb is suitably formed of a transparent plastic material adapting side walls 88 and 90 to flex or move toward and away from one another according to the pressure in gaseous region 86 within the drip bulb. The side walls 88 and 90 are provided respectively with attachment buttons 36 and 44 which are rigidly secured to the side walls and which are respectively received within the upwardly facing notches ofsupport straps 30 and 40.

\ ConsequentlY, as pressure changes within the drip bulb, the side wall 90 moves away from or toward side wall 88 and will flex the support strap 40 relative to support strap 30. Since hard rubber connecting rod 60 is joined to strap 40, flexure of strap 40in this manner will move magnetically permeable core 58 back and forth with respect to bobbin-56.

The upper U-shaped notches 34 and 42 in support straps 30 and 40 are narrowed slightly at the top as-can be seen in FIG. 2, whereby the neck portions of the attachment buttons 36 and 44 snap into place, so the drip bulb 38 is securely held. However, the bulb can be removed from strap supports 30 and 40, for replacement, by urging the same upwardly.

Reference is now made to FIG. 3 illustrating acircuit arrangement according to the present invention and schematically illustrating the connection of the transducer including the above-mentioned bobbin 56. Bobbin 56 is provided with a primary winding 96, suitably connected to a 6volt alternating current source, and a pair of differentially related secondary windings 98 and 100. The secondary windings 98 and 100 are reversely connected in series in the usual manner, for the transducer such that, for a given central position of core 58, a voltages induced in secondary windings 98 and 100 balance, and substantially no net output results. Adjusting screw 70 is set for the proper positioning of drip bulb 38 with respect to support strap 40, taking into consideration the width of the bulb. Thus, movement of adjusting screw 70 adjusts the static pressure applied to the drip bulb since screw 70 bears upon support strap 30 on one side of drip bulb 38 while support strap 40 bears on the remaining side of drip bulb 38. The

. 4 pressure applied in this manner is desirably such that the drip bulb can either expand or contract as a result of gaseous pressure therewithimAdjusting screw 64, which moves the transducer bobbin 56 back and forth,

' is employed for centering meter 102 which is coupled to the secondary coils. Meter l02'desirably has a zero center position, and when bobbin 56 is positioned by screw 64 such that the voltages induced in windings98 and are equal, meter 102 is centered. Then, as the drip bulb expands or contracts, resulting in the movement of core 58, a differential output as between the coils will causethe meter to read in the positive or negative direction. The meter is suitably calibrated according to the pressure within the drip bulb.

The windings 96, 98 and 100 are illustrated schematically in FIG. 3, it being understood the same will generally be wound around bobbin 56. A rectifying diode 104 and an adjustable resistance 107 are serially disposed between one leg of the secondary coil connection and meter 102, while a capacitor 106 shunts the meter to provide do charge storage and higher meter readings. It will be appreciated that anamplifier may be disposed between the coils and the diode if desired so that more sensitive pressure readings can be taken. Furthermore, the pressure indicating electrical output may be connected to automatic control circuitry for taking a desired action in response to a pressure reading, for example shutdown of treatment equipment in response to incorrect pressure. In any case, the disadvantages of prior art systems wherein a remote pressure diaphragm is connected to a drip bulb are alleviated. Damage to and contamination of pressure-measuring equipment is avoided, and contamination of the liquid, e.g., blood in the case of a dialysis system, is also avoided.

While I have shown and described a preferred embodiment of my invention, it will be apparent to those skilledin the art that many changes and modifications may be made without departing from my invention in its broader aspects. I therefore intend the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

I claim:

1..A drip bulb adapted to be supported in a vertical position for providing the vertical dispensing of liquid droplets through a gaseous region into a quantity of liquid contained in said drip bulb, and adapted to be pressure-responsive, said drip bulb comprising;

a containerbody for holding said quantity of liquid, said body having an opening proximate the top thereof for ingress of liquid and having an opening proximate the bottom thereof for egress of liquid,

wherein said drip bulb is'provided with at least one flexible side wall,

and movement-responsive means adapted to detect movement of said side wall as the result of pressure changes within said drip bulb.

2. The drip bulb according to claim 1 wherein said flexible wall is one of a pair of spaced flexible walls of said drip bulb. 3.The drip bulb according to claim 1 wherein said drip bulb is elongate in horizontal cross section, said flexible wall being one of a pair of spaced larger walls of said drip bulb providing said drip bulb with a flattened, pressure-responsive configuration.

4. The drip bulb according to claim 2 provided with attachment buttons secured to. the spaced walls of said drip bulb wherein said buttons are engageable for ascertaining relatve movement between said walls.

5. Pressure gauge means comprising:

a drip bulb adapted to receive liquid and having a gaseous layer above a quantity of liquid in said drip bulb, said drip bulb having a flexible wall responsive in movement to pressure within said drip bulb,

a movement-responsive transducer adapted to provide an output related to relative movement,

and means for coupling said transducer to said flexible wall whereby the movement of said flexible wall causes a change in output from said transducer.

6. The apparatus according to claim 5 wherein said transducer comprises plural electrical coil means one of which is connected to a source of alternating current, said transducer further including a movable core coupled by said'coupling means to the wall of said drip bulb whereby movement of said wall changes the electromagnetic coupling between one of said coil means and other coil means of said transducer.

7. The apparatus according to claim 6 including a pressure-reading meter coupled to said other coil means.

8. A pressure-measuring device comprising:

a drip bulb having upper and lower liquid connections and having a pair of facing flexible walls provided with attachment means wherein a variation of pressure inside said bulb expands and contracts said walls toward and away from one another,

a first support for engaging one of said attachment means,

a second support for engaging the remaining attachment means, said second support being relatively movable as said facing walls of said drip bulb move toward and away from one another,

and a transducer having a movable element attached to said second support for providing an output'as said second support moves relative to said first support.

9. The apparatus according to claim 8 further including a chamber for slidably receiving the transducer,

adjustment means for slidably moving said transducer in said chamber relative to the movable element of said transducer,

and spring-biasing means for urging said transducer in said chamber toward said adjustment means.

10. The apparatus according to claim 9 further including second adjustment means for moving said first support toward said drip bulb.

11. The apparatus according to claim 8 further including a substantially U-shaped frame having said supports attached to the inside legs of the U, said drip bulb being partially received between the legs of the U.

12. The apparatus according to claim 8 wherein said frame includes an adjustable clamp for securing said frame to a vertical support rod.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION I PATENT NO. 3,841,157

DATED I October 15, 1974 INVENTOR(S) Charles B. Willock It is certified that error appears in the above-identified patent and that said Letters Patent are hereby c 0rrected as shown below: I I

In the title, "DROP" should be -DRIP.

Column 3, line 19, "of" should be --or-.

Column 3, line 35, "ConsequentlY" should be --Consequently. Column 3, line 54, ng should be six-volt-.

Signed and sealed this 20th day of May 1975.

(SEAL) Attest:

C. MARSHALL DANN RUTH c. MASON Commissioner of Patents Attesting Officer and Trademarks 

1. A drip bulb adapted to be supported in a vertical position for providing the vertical dispensing of liquid droplets through a gaseous region into a quantity of liquid contained in said drip bulb, and adapted to be pressure-responsive, said drip bulb comprising; a container body for holding said quantity of liquid, said body having an opening proximate the top thereof for ingress of liquid and having an opening proximate the bottom thereof for egress of liquid, wherein said drip bulb is provided with at least one flexible side wall, and movement-responsive means adapted to detect movement of said side wall as the result of pressure changes within said drip bulb.
 2. The drip bulb according to claim 1 wherein said flexible wall is one of a pair of spaced flexible walls of said drip bulb.
 3. The drip bulb according to claim 1 wherein said drip bulb is elongate in horizontal cross section, said flexible wall being one of a pair of spaced larger walls of said drip bulb providing said drip bulb with a flattened, pressure-responsive configuration.
 4. The drip bulb according to claim 2 provided with attachment buttons secured to the spaced walls of said drip bulb wherein said buttons are engageable for ascertaining relatve movement between said walls.
 5. Pressure gauge means comprising: a drip bulb adapted to receive liquid and having a gaseous layer above a quantity of liquid in said drip bulb, said drip bulb having a flexible wall responsive in movement to pressure within said drip bulb, a movement-responsive transducer adapted to provide an output related to relative movement, and means for coupling said transducer to said flexible wall whereby the movement of said flexible wall causes a change in output from said transducer.
 6. The apparatus according to claim 5 wherein said transducer comprises plural electrical coil means one of which is connected to a source of alternating current, said transducer further including a movable core coupled by said coupling means to the wall of said drip bulb whereby movement of said wall changes the electromagnetic coupling between one of said coil means and other coil means of said transducer.
 7. The apparatus according to claim 6 including a pressure-reading meter coupled to said other coil means.
 8. A pressure-measuring device comprising: a drip bulb having upper and lower liquid connections and having a pair of facing flexible walls provided with attachment means wherein a variation of pressure inside said bulb expands and contracts said walls toward and away from one another, a first support for engaging one of said attachment means, a second support for engaging the remaining attachment means, said second support being relatively movable as said facing walls of said drip bulb move toward and away from one another, and a transducer having a movable element attached to said second support for providing an output as said second support moves relative to said first support.
 9. The apparatus according to claim 8 further including a chamber for slidably receiving the transducer, adjustment means for slidably moving said transducer in said chamber relative to the movable element of said transducer, and spring-biasing means for urging said transducer in said chamber toward said adjustment mEans.
 10. The apparatus according to claim 9 further including second adjustment means for moving said first support toward said drip bulb.
 11. The apparatus according to claim 8 further including a substantially U-shaped frame having said supports attached to the inside legs of the U, said drip bulb being partially received between the legs of the U.
 12. The apparatus according to claim 8 wherein said frame includes an adjustable clamp for securing said frame to a vertical support rod. 